Ahh, the concaves, the damn ironic relationship I have with concaves. One of my intense turn ons, is when I see an inflatable (myler foil or PVC) that has a concave section, it's the part that just sparks that beautiful fire inside. However, between my PVC hammers, PVC 36 inch penguins, and my 30 inch inflatable white and teal mylar football jersey shapes, they have all sprung leaks at rather low inflation tolerances. However not all is bad, as conversely the few black and gold "saints" football jerseys are quite strong and simply get a bit stretched.
So I would surmise that the concave weakness or issue is something to do with the physics of pressure, stress or seam strength, or have I just ended up with a heap of duds.
So I would surmise that the concave weakness or issue is something to do with the physics of pressure, stress or seam strength, or have I just ended up with a heap of duds.